Ventilating fan



Sept. 29, 1931- c. A. HENDRICKSON VENTILATING FAN Filed April '12, 1929 gwve'nto'c 670210 /3 flandric/wob.

duomwq Patented Sept. 29, 1931 UNITED STATES- canon a. ammoxsox, or nmwaa, comaano mmn'rmo ran Application filed Apr-111B, 1929. Serial 36o. 854,554,

This invention relates to improvements in ventilating fans of the t employed for expelling air from buil ings and for circulati air for the purpose of heatmg l and venti ating.

It is the ob ect of this invention to produce a fan of the t e above mentioned which shall have a arge capacity and a h' h efiiciency.

t is a further object of this inventlon to rovide means for mounting the motor wh1ch will prevent the noises produced oy the roller bearings from bein transmitted to the support and magnifie Another object of this invention is to produce a fan construction which shall prevent to as great an extent as practicable a slippage of air about and through the propeler when the same is operatin I The above and other ob'ects which will become apparent as the escription proceeds are attained by means of a constructionnnd an arrangement of parts which will now be described in detail and reference for this urpose will be had to the accom anying rawin in which the preferre embodiment the invention has been illustrated and in which:

Fig. 1 is a side elevation of the fan'look- 1n the direction of arrow 1, in Fi '2' ii 2 is a section taken on line E1 the drawings numeral 1 represents the circular ring portion of the frame in which the motor 2 is mounted. This frame is providedwith three radial arms 3 whose inner ends terminate in'a ring 4. These arms are curved outwardly so asto be spaced from the plane of the ring in the manner shown quite clearly in Fig. 2. In the example'illustratcd the motor is of the circular type and has secured to it a split rindgnE that is provided with outwardly exten g lugs or cars 6 which are perforated for the rece tion of a clamping bolt 7 in the manner s own in Fig. 4. A sheet of rubber, felt or other resilient material is placed between the outer surface of the motor and the inner surface of ring so as to provide a layer of material that will not transmit sound vibrations from the'motor to the ring. In the drawings, the material 8 has been shown as constituting a complete ring but it is possible to have several sections of this material spaced apart if any advanta e should be found in this construction. 'Fhe ring 5 is provided with a plurality of radially extendlng lugs 9 of which three have been shown in the drawings and these are provided with threaded openings for the reception of the cap screws 10 which extend through openings in rin 4 and serve to hold the motor in place. %Vhen the motor is mounted in the manner shown and above described, it will be held very securely in such a position that its shaft will be concentric with the ring 1 and any sounds or noises produced by the ball or ro ler bearings will be prevented from reaching the ring 1 and the surface on which this is mounted, and therefore they will not be magnified as they otherwise would be if the motor were connected with the ring by metallic means through which the sound waves could be readil transmitted. Secured to the shaft 11 of the motor is a fan. fan has been shown as provided with four blades forming two diametrically located piiirs spaced ninety degrees apart. The

ades are of the aeroplane type as these 'have been found to move through the air with the greatest efliciency. Although four blades have been shown, it is, of course, possible to employ a smaller or greater number ofblades, but with the speed of rotation employed with this type of fan'and thev moderate diameter of the fans, four blades have been found to operate quite successfully. Fans of this typeare intended to force air. in the direction of the arrows in Fig. 2 and are usually attached to the end In theexample illustrated this of the cylindrical duct or conduit which has been shown b dotted lines and which has been indicate by reference numeral 12, Fig. 2. It is apparent that when the fan is in operation that the air pressure'on the delivery side will be increased over that on the intake side and therefore there is a constant tendenc for the air to flow backwardlg from the elivery side to the intake side.

me of this air will return through the space between the outer tips of the fan and the inner surface of ring 1, but as this can be made very small the slippage at this point can be decreased to a very small amount. It is evident that ifthe fan had only two blades and was rotating at ordinary speed that there would be a great opportunity or slippage through the opening between the blades, and it has therefore been customary to rovide fans of this type with a larger num r of blades so as to reduce the tendency for slip age. In the fan illustrated and described t e fans have each been provided with a rearwardly extending projection 13 on the following side and near the outer ends. The width of this projection has been calculated so that at the normal rate of speed the time that it takes the fan blades to rotate through ninety degrees minus the angular width 0 the fan and pro- ,jection is less than the time necessary for the air to reverse and flow to the other side of the fan and therefore when the fan is rotating at normal speed, there can be no sli page of air between the fan blades near t e eripheries as this is prevented by the presence of the lugs or projections 13. There is also another place where air usually flows rearwardly through a ventilating fan and this is a circular ace concentric with the axis of rotation. Ihis is due to the fact that at this point the lineal velocity of the blades is much less than at points farther removed from the axis and besides this the fan portion of, the blade usually terminates before it reaches the center with the result that there is very little fan action in the zones directly surrounding the axis of rotation, and therefore unless some means is provided to prevent it, air will return from the delivery side to the, intake side of the fan in this zone. To prevent slippage around the center of the fan, 'I have provided the latter with a circular barrier 15 which also serves to connect the root portions of the fans 16. When the fan is provided with a barrier like that indicated by'reference numeral 15 and has the following edges of the fans provided with extensions 13, the amount of slippage can be reduced to a negligible quantity without decreasing the efliciency of the fan.

From Figs. 5 and 6 it will be seen that the front surfaces of the parts 13 lie in the plane of rotation and are not intended to assist in propelling the air, but as abovev explained, their function is to prevent a return flow of air or slippage at these points. As the fan blades are practically of uniform width and sincethey rotate at all points along their length at the same angular velocity, it is apparent that there is a greater tendency to slippage near the outer ends of the fan than at any other point along their length, except the center as above described.

In the drawings I have shown a plug connector 17 which is secured to the frame and from which a cable 18 extends to the motor. Connection with the power is made by means of a plug 19 and the speed of-the motor can be controlled by means of a switch 20 which also serves to stop and start the motor.

From the above description it will be seen that I have produced a ventilating fan of a simple and substantial construction in which the motor is mounted by a means which serves to deaden the sound and therefore revent the noises from the bearings from ing magnified to any appreciable extent and in which the fan is so constructed that the slippage of air is reduced to a negligible amount without thereby increasing the amount of wer per unit of air handled.

Having escribed the invention what isv claimed as new 1s:

A ventilator fan comprising a hub provided with a pluralit 0 narrow fan blades that extend radially mm the hub, the front sides of the blades being fiat and inclined to the plane of rotation, the rear sides being convex, theouter end of each blade being provided with a ti that extends from one side thereof and w ch lies substantially in the plane of rotation.

In testimon whereof I afiix my signature.

UD A. HENDRICKSON. 

